1. Field of the Invention
The present invention relates generally to electronic pump control systems and, more particularly, to electronic pump control systems to disable or shut down the pump upon a low fluid condition.
2. Description of the Prior Art
Pumping systems for transferring liquid out of a container are well known in the art. Most pumping systems do not require that the amount of liquid being pumped be measured for example, in sumps, sewer treatment facilities, and general drainage. However, in pump systems for the dispensing of agricultural chemicals and the like that are to be mixed with water or other diluent, it is important to accurately measure the amount of chemical being dispensed. This is because the concentration of chemicals and dilution rates can affect the product application and/or effectiveness.
In response to the above, pump controllers have been devised to work in conjunction with the pump to meter out required amounts in response to inputted or selected amounts or volume of liquid. Once the desired volume of liquid has been pumped as determined by the controller, the controller shuts off the pump. At this point, the diluent may be added to the chemical. In cases where the chemical is not diluted, precise volume amounts generally also need to be known. In some systems, a device, such as a flowmeter, is used to provide flow data for determining the volume of liquid pumped. The device is in communication with the pump controller. A drawback to these systems, however, is that they provide false readings regarding volume pumped when the source tank of liquid becomes empty as the flow of air will be registered by the flowmeter as liquid flow.
In the prior art, some pumping systems have utilized pressure devices in the flow lines to determine pressure differentials in order to control the pump. Other systems have sensed pump rotation to determine fluid flow rate. Still, other systems utilize liquid level sensors in the source tank to monitor fluid level.
All of these systems require additional sensors, and in the case of liquid level sensors, the source tank must have the sensors therein. To date there is no simple and efficient system for indicating when the fluid source tank becomes empty without having a myriad of sensors. If the fluid source tank becomes empty and the system continues believe that something is being pumped, inaccurate measurement of the fluid will result. One cannot be by the pumping system at all times in order to monitor fluid flow. Also, the use of additional indicia equipment is cumbersome and objectionable.
Therefore, it is an object of the present invention to provide a simple method whereby the pump is shut off when the fluid source becomes empty.
It is another object of the present invention to provide a method whereby the pump controller in conjunction with the flowmeter can determine whether or not the fluid source tank is empty without the use of tank liquid level indicia equipment.
It is also an object of the present invention to provide an apparatus for the same.